Tag: map

Detailed explanation of java HashMap source code

Article directory Detailed explanation of java HashMap source code HashMap source code 1 put method process 2 expansion 3 get method Detailed explanation of java HashMap source code Java HashMap is an implementation of the Map interface based on a hash table, which can store a data structure of key-value pairs. The characteristics of HashMap […]

μC/OS-II—Semaphore management 1 (os_sem.c)

Directory Semaphore management Semaphore creation Semaphore deletion Get/wait for semaphore emit semaphore Semaphore management Semaphore creation OS_EVENT *OSSemCreate (INT16U cnt) {<!– –> OS_EVENT *pevent; #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif #ifdef OS_SAFETY_CRITICAL_IEC61508 \t if (OSSafetyCriticalStartFlag == OS_TRUE) {<!– –> OS_SAFETY_CRITICAL_EXCEPTION(); return ((OS_EVENT *)0); } […]

C++: Encapsulation principle of map and set

Article directory Red-black tree packaging Encapsulation of map and set Implementation of red-black tree iterator Implementation of operator + + and — ++ implementation process Other modules for iterators For implementing const solution to set map solution overall implementation This article was written after the red-black tree simulation was implemented, and map and set were […]

JavaCollection (3) Map

1. Characteristics of Map interface implementation class 1)Map and Collection exist side by side. Used to save data with mapping relationships: Key-Value 2) The key and value in the Map can be any reference type data and will be encapsulated into the HashMap$Node object. 3) Keys in Map are not allowed to be repeated 4) […]

[vue+amap] Gaode map draws polygonal area

Reference documentation: Amap Reference Manual Amap sample code 1. Create an application in the Amap console and obtain permission ak Gaode map console Ps. In this project, basic controls such as buttons use the element-ui version control. 2. Global introduction within the project Introduce the Amap code into index.html: <script type=”text/javascript”> window._AMapSecurityConfig = {<!– –> […]

Semaphores–System V semaphores and Posix semaphores

What is a semaphore A semaphore is a counter used to control access to resources shared by multiple processes/threads. Often used together with locks. When a process/thread is accessing a resource, the semaphore can prevent another process/thread from disturbing it. Producer and consumer models are typical uses of semaphores. Why are there two sets of […]

Arduino + OLED screen display bitmap

original There are already many projects using Arduino to drive a 0.96-inch OLED screen to display various information. If we need to drive OLED to display images, logos, etc. whatever we want, here is a simple and general method. You need to use Image2Cp, a tool for converting images to CPP code. Component list Arduino×1 […]

The H5 page based on vue 2.0 uses H5’s own positioning, Amap positioning, search for surrounding merchants, coverage markers, and positioning to the current city.

Use Gaode map positioning, search for surrounding merchants, and cover markers in the Vue-based H5 page First install the Amap plug-in npm i @amap/amap-jsapi-loader –save Map hosting container <template> <div id=”container”></div> </template> Map container style <style scoped> #container{<!– –> padding:0px; margin: 0px; width: 100%; height: 800px; } </style> Introduce JS API Loader, initialize the map, […]

Use the Stream stream to convert the obtained object List＜Object＞form data into Map＜Grouping conditions, quantity statistics＞form

For example, the current business needs to group the obtained data, and then use another method to process the data. The methods used are Collectors.groupingBy, Collectors.counting(), Collectors.reducing(). Then, take the following example as an example to collect the obtained lists and group the obtained data by gender, with gender as K and the number of […]